Researching Patterns and Processes of Macroevolution

My research involves using the fossil record to study macroevolutionary patterns and processes. A central part of my research involves reconstructing phylogenetic patterns in arthropods, especially trilobites. I am also interested in the role that earth history changes, such as tectonic changes and climatic changes, play in influencing evolution. For this reason a central part of my research involves paleobiogeography.

The Lieberman Lab

Research in Bruce Lieberman's Lab

Research on the nature and timing of the Cambrian radiation

Studies of evolutionary patterns in trilobites

I have used phylogenetic biogeographic approaches to determine the relationship between earth history change and evolution and also to reconstruct the sequence of Paleozoic tectonic events. One of the time intervals my research has focused on is the Cambrian radiation: that key episode in the history of life when diverse, abundant animal remains appear in the fossil record. I have conducted phylogenetic analyses of the diverse olenellid trilobites and used these to study evolutionary and biogeographic patterns during the radiation.

Phylogenetic and biogeographic patterns suggest that the radiation of trilobites may have been underway in the late Neoproterozoic before the group becomes manifest in the fossil record; these patterns also suggest that the breakup of a supercontinent at the end of the Neoproterozoic had an important effect on the topology of the Cambrian radiation. I've also used probabilistic models to study how fast the rates of evolution were during this interval and the results suggest that rates of evolution were high at the time but not so high that new rules of evolution need to be invoked to explain the Cambrian radiation.

This research has been supported by
the National Science Foundation and the National Geographic Society and has involved fieldwork in the Mackenzie Mountains, Northwest Territories,
Canada in collaboration with Mike Pope
at Washington State University.

Studies of Burgess Shale type fossils

With support from the National Science Foundation we studied evolutionary and biogeographic patterns in a Middle Cambrian soft-bodied fauna from Utah. This work was conducted with my former post-doc, Jon Hendricks, and involves collaboration with Derek Briggs, Bob Gaines, and Mary Droser. We have described new taxa from these localities and have also conducted phylogenetic analyses on a series of new arachnomorph taxa that have been recovered from these localities. In addition we conducted biogeographic studies on these taxa using phylogenetic biogeographic analyses and Geographic Information Systems (GIS), the latter in conjunction with Alycia Stigall at Ohio University. Finally, we documented beautifully preserved jellyfish from the Middle Cambrian of Utah. These appear to represent modern crown groups, including modern orders, families, and in one case a genus. This work has also been made possible through the generous contributions of specimens by the Gunther family, and Sue Halgedahl and Richard Jarrard, along with the insight and assistance of Richard Robison.

Research in Paleobiogeography

I am very much interested in paleobiogeographic studies and this has formed an important component of my research. This not only includes my research described above under the heading of the Cambrian radiation but various other theoretical and practical applications. Much of this research has involved phylogenetic approaches.

This research has also included applying Geographic Information Systems (GIS) and Ecological Niche Modeling (ENM) to study biogeographic patterns in deep time using the fossil record. Some of this work was done in conjunction with my former student Alycia Stigall, who is now an associate professor at Ohio University, and involved exploring ecology and evolution during the Late Devonian biodiversity crisis. Other research with her and my former post-doc Jon Hendricks involving a GIS based analysis of paleobiogeographic and evolutionary patterns in Cambrian Burgess Shale type faunas is provided above under the heading of research on the Cambrian radiation.

My lab has also been very interested in using GIS to explore the role that competition plays in influencing macroevolution. My current student Cori Myers and I conducted a GIS based analysis of the charismatic marine vertebrate fauna of the Cretaceous Western Interior Seaway. Our results suggest that in the Cretaceous, and perhaps in general at the grand scale of the history of life, environmental factors played a much more prominent role in structuring geographic distributions, and causing extinction, than interspecific competition. We are continuing to do ENM based work on this fascinating time period.

Research in Astrobiology

In collaboration with Adrian Melott and other scientists, and with support from NASA, we have been conducting research investigating the nature of the late Ordovician mass extinction and the extent to which it may have been precipitated by a Gamma Ray Burst. This research is described more fully at: http://kusmos.phsx.ku.edu/~melott/Astrobiology.htm

Investigating Large Scale Patterns in the History of Life

As part of my research interests in macroevolution and biogeography, one of the topics I have considered is the evidence that at the large scale physical factors play a fundamental role in influencing macroevolution. This has included investigating the evidence that there is a fundamental connection between carbon dioxide levels and rates of evolution and extinction; this work was conducted in collaboration with Bob Goldstein and my former student, Jim Cornette; we found strong evidence that carbon dioxide levels and rates of macroevolution are significantly coupled. In addition, in work led by Jim Cornette, I investigated the extent to which the history of Phanerozoic diversity can be modeled as a random walk; we found strong evidence that except for the last 75 million years life largely follows a trajectory indistinguishable from a random walk. This does not mean that the history of diversity over the last 520 million years is random, and instead it may be that diversity is largely tracking environmental variables that themselves are following a random walk pattern. Most recently, and associated with my work in the area of astrobiology described above, I have been collaborating with Adrian Melott to consider the evidence that there are large scale cycles in biodiversity, possibly associated with astrophysical phenomena.

Investigating Phylogenetic Patterns in Cheirurid Trilobites

Information on various trilobite species, especially emphasizing cheirurids but including many other clades, is available at the link above. This includes geographic distributions, phylogenetic patterns, and photographs.

We have been funded by NSF, through their RevSys program in Systematic Biology, to investigate phylogenetic patterns in a diverse clade of phacopid trilobites, the cheirurids. The other PI on the grant is Jonathan Adrain at the University of Iowa. We are using the phylogenies to produce a stable, modern classification for the group, and also to understand biogeographic patterns and macroevolution in this major invertebrate clade. This includes a consideration of patterns of speciation and extinction during a key episode in the history of life, the Late Ordovician mass extinction. I am working closely with Ph.D. students Curtis Congreve and Wes Gapp. We have produced a phylogenetic hypothesis for the Deiphonine trilobites, a subfamily of Cheiruridae and conducted a biogeographic analysis on the group. This work has been published in the Journal of Paleontology. We have also produced a phylogenetic hypothesis for the Sphaerexochinae. We have also investigated phylogenetic patterns in a closely related group of trilobites, the Homalonotidae. These have a different life history strategy than many cheirurids and also occupy different environments. Thus they provide an excellent point of comparison to consider macroevolutionary patterns and processes and how these may vary among trilobite groups. Finally, with Francine Abe, who recently completed her Ph.D. with honors, I have been investigating phylogenetic, biogeographic, morphometric, and macroevolutionary patterns and processes in another group of phacopid trilobites, the calmoniids. Patterns in these suggest that geological and geographic complexity plays an important role in spurring evolutionary radiations.

We are currently funded by NSF through their Advancing the Digitization of Biological Collections (ADBC) program to create and develop a new digital collections network that will help expand the insights about biogeography and evolution that can be made through study of fossils held in several museum collections. To this end we are entering information about the age and precise geographic location of fossil specimens from parts of several key paleontological collections into electronic databases. This will involve the use of various computer programs to database and precisely localize specimens. Our efforts will consider nearly 450,000 specimens belonging to 900 species from several museums throughout the U.S., and will focus on three different time periods in the history of life. We are also creating an on line digital atlas illustrating and describing these fossils and providing maps showing where they can be found, "The Digital Atlas of Ancient Life." We will also create an "app" so these atlases can be used on handheld devices out in the field.

The museum collections and fossils provide large amounts of data useful for studying what causes species to migrate, go extinct, or evolve over long time periods. They are of great relevance for considering how global change has and will continue to effect life on this planet. This work is in collaboration with co-PI s Una Farrell, collections manager in the Division of Invertebrate Paleontology, and Jim Beach, Specify project director, both at KU, as well as PI s Jonathan Hendricks from San Josť State University and Alycia Stigall at Ohio University (as well as their partners).

To learn more about the Integrated Digitized Biological Collections (iDigBio) program we are involved with please visit the iDigBio site.

Developing Likelihood Methods for Phylogenetics of Fossil Taxa Using Trilobites as a Model System

I am working with Mark Holder, Department of Ecology and Evolutionary Biology, University of Kansas, and Tracy Heath, Department of Integrative Biology, University of California, Berkeley, to improve maximum likelihood based methods for analysis of morphological data, especially involving data from fossil taxa. We will also develop improved methods for calculating speciation and extinction rates, including for phylogenies that incorporate both fossil and extant taxa. Our project will take advantage of the dense fossil record of trilobites, along with the rich phylogenetic information available for the group. More information on this project is provided at the following site: Trilogenetics

Current Students

Ian Wesley Gapp, who is investigating phylogenetic and biogeographic patterns in Cambrian trilobites to study macroevolutionary patterns during the Cambrian radiation wes123@ku.edu

Erin Saupe, (co-advise with Paul Selden) who is using ecological niche modeling to investigate how climate change effects the evolution and biogeography of extant and fossil species eesaupe@ku.edu